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Limit Modes of Particulate Materials Classifiers
Adamčík, Martin ; Štěpánek, František (referee) ; Fekete, Roman (referee) ; Svěrák, Tomáš (advisor)
S požadavky materiálových věd na stále menší částice jsou potřebné i nové přístupy a metody jejich klasifikace. V disertační práci jsou zkoumány struktury turbulentního proudění a trajektorie částic uvnitř dynamického větrného třídiče. Zvyšující se výpočtový výkon a nové modely turbulence a přístupy modelování komplexních plně turbulentních problémů řešením Navier-Stokesových rovnic umožňují zkoumání stále menších lokálních proudových struktur a vlastností proudění s větší přesností. Částice menší než 10 mikronů jsou více ovlivnitelné a jejich klasifikace do hrubé nebo jemné frakce závisí na malých vírových strukturách. Práce se zaměřuje na podmínky nutné ke klasifikaci částic pod 10 mikronů, což je současná hranice možností metody větrné separace. CFD software a poslední poznatky modelování turbulence jsou použity v numerické simulaci proudových polí dynamického větrného třídiče a jsou zkoumány efekty měnících se operačních parametrů na proudová pole a klasifikaci diskrétní fáze. Experimentální verifikace numerických predikcí je realizovaná prostřednictvím částicové anemometrie na základě statistického zpracování obrazu (PIV) a proudění lopatkami rotoru je vizualizováno. Predikované trajektorie částic jsou experimentálně ověřeny třídícími testy na větrném třídiči a granulometrie je určená pomocí laserové difrakční metody. Zkoumány jsou Trompovy křivky a efektivita třídění.
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Formulation and processing of pharmaceutical nanosuspensions
Lehocký, Róbert ; Štěpánek, František (advisor) ; Šklubalová, Zdeňka (referee) ; Rajniak, Pavol (referee)
The pharmaceutical industry has been bringing an increasing number of innovative active ingredients from BCS Groups II and IV to the market in recent decades. Among other things, these substances are characterized by very low solubility in water. In order for these sparingly soluble substances to be used effectively in the treatment of patients, it is necessary to increase their solubility and thus induce a sufficient plasma concentration. One way to solve this problem is to adjust the crystal size of the drug substance to the level of micro- and nanoparticles. Thanks to particle size adjustment, it is possible to adjust the specific surface and thus control the solubility and overall dissolution profile of the drug. The thesis is divided into three parts. The first part deals with the effective preparation of a nanosuspension of sparingly soluble prodrug by means of nanomilling and subsequent transfer and scale-up from a batch to a flow-through bead mill by a novel method based on the effective number of passes. The second part concentrates on the description of an adverse but interesting effect - the occurrence of the so called Pickering foam, which is formed during the grinding process in a flow-through bead mill. The work explains the mechanism of Pickering foam formation and suggests a way to...
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Al Qaeda in Unstable States - Simalia and Pakistan
Štěpánek, Filip ; Kofroň, Jan (advisor) ; Doboš, Bohumil (referee)
Abstract This paper examines how the decay of political power and other territorial characteristics affect al-Qaeda's chances of successfully building regional cells in weak and collapsed states. Its focal point is a comparison between a case study of the FATA region of Pakistan and Somalia. It aims to uncover factors that negatively affected the functioning of the actor in Somalia, but which did not negatively affect staying in FATA. As a result, we find that the factors mentioned are mainly related to the area of recruitment, the potential for forging new alliances, security risks associated with the absence of a central authority, and the toll of deteriorating infrastructure. This observation is interesting as the FATA region presents a similar socio-political environment to Somalia. In the literature, we encounter the view, demonstrated by the case of Somalia in particular, that failed states are not ideal for terrorist groups to operate. It is therefore interesting for us to identify the reasons why al-Qaeda turned out fundamentally differently in the two cases. The author interprets the results in such a way that it is not possible to over-generalize the aforementioned lesson, and further comparative studies are necessary for this reason
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Preparation of pharmaceutical formulations based on polymeric and lipid carriers
Kubačková, Jana ; Zbytovská, Jarmila (advisor) ; Panáček, Aleš (referee) ; Štěpánek, František (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Candidate Mgr. Jana Kubačková Supervisor Assoc. Prof. Jarmila Zbytovská, Mgr., Dr. rer. nat. Co-supervisor PharmDr. Ondřej Holas, PhD. Title of Doctoral Thesis Preparation of pharmaceutical formulations based on polymeric and lipid carriers Nanomedicine allows application of nanoscaled drug delivery carriers to achieve a therapy that can be tailored in terms of e.g. controlled release, site-specific delivery and protection of an active substance. From multiple nanoplatforms available for drug delivery, advantage was taken of biocompatible and biodegradable polymers and lipids to enable targeted intracellular delivery, delivery of a poorly water-soluble drug and delivery of a sensitive macromolecule. In the study with biodegradable polymeric nanomaterial we worked with experimental poly(lactic-co-glycolic acid) (PLGA) polymers. The formulations were optimised for targeting to phagocytic macrophages - of size up to 300 nm and negative surface charge. For this purpose, two linear and one branched PLGA were screened in combination with one of four surfactants in low concentrations (0.1-1%). These PLGA polymers were formulated into nanoparticles and loaded with a hydrophilic fluorescent dye Rhodamine B...
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Preparation of pharmaceutical formulations based on polymeric and lipid carriers
Kubačková, Jana ; Zbytovská, Jarmila (advisor) ; Panáček, Aleš (referee) ; Štěpánek, František (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Candidate Mgr. Jana Kubačková Supervisor Assoc. Prof. Jarmila Zbytovská, Mgr., Dr. rer. nat. Co-supervisor PharmDr. Ondřej Holas, PhD. Title of Doctoral Thesis Preparation of pharmaceutical formulations based on polymeric and lipid carriers Nanomedicine allows application of nanoscaled drug delivery carriers to achieve a therapy that can be tailored in terms of e.g. controlled release, site-specific delivery and protection of an active substance. From multiple nanoplatforms available for drug delivery, advantage was taken of biocompatible and biodegradable polymers and lipids to enable targeted intracellular delivery, delivery of a poorly water-soluble drug and delivery of a sensitive macromolecule. In the study with biodegradable polymeric nanomaterial we worked with experimental poly(lactic-co-glycolic acid) (PLGA) polymers. The formulations were optimised for targeting to phagocytic macrophages - of size up to 300 nm and negative surface charge. For this purpose, two linear and one branched PLGA were screened in combination with one of four surfactants in low concentrations (0.1-1%). These PLGA polymers were formulated into nanoparticles and loaded with a hydrophilic fluorescent dye Rhodamine B...
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Design and synthesis of surface architectures on fluorescent nanodiamonds
Havlík, Jan ; Kotek, Jan (advisor) ; Lang, Kamil (referee) ; Štěpánek, František (referee)
anks to their unique properties and high biocompatibilities, fluorescent nanodiamonds are promising representatives of modern carbon nanomaterials with a broad range of applications. Nevertheless, their wider use is limited because of weak fluorescence intensity and low colloidal stability in the biological environment. e optimization of treatment procedures and development of new suitable surface designs is therefore critically needed. In this study, several key steps for fluorescent nanodiamond treatment have been optimized, leading to both a substantial increase in fluorescence intensity and to significantly lower surface damage caused by graphitization. Further, a new high-throughput irradiation technique was developed. e influence of surface chemistry on the fluorescence parameters was studied using partial fluorination of the functional groups on the nanodiamond surface. A novel method which significantly affects the interaction of nanodiamonds with biological systems by increasing of the homogeneity and circularity was developed. e potential of nanodiamonds for future medical and biological research was demonstrated on particles with complex surface architectures that enabled targeting and therapy of tumor cells. Moreover, a strong and highly selective affinity of fibroblast growth factors to diamond...
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Breaking of Rod-shaped Model Material during Compression.
Kulaviak, Lukáš ; Pěnkavová, Věra ; Růžička, Marek ; Punčochář, Miroslav ; Zámostný, P. ; Grof, Z. ; Štěpánek, F. ; Schöngut, M. ; Havlica, Jaromír
The breakage of a model anisometric dry granular material caused by uniaxial compression was studied. The bed of uniform rod-like pasta particles (8 mm long, aspect ratio 1:8) was compressed (Gamlen Tablet Press) and their size distribution was measured after each run (Dynamic Image Analysing). The compression dynamics was recorded and the effect of several parameters was tested (rate of compression, volume of granular bed, pressure magnitude and mode of application). Besides the experiments, numerical modelling of the compressed breakable material was performed as well, employing the DEM approach (Discrete Element Method). The comparison between the data and the model looks promising.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22018011012170 - PDF
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Powder Rheology of Nanocrystalic Particles.
Kulaviak, Lukáš ; Pěnkavová, Věra ; Růžička, Marek ; Punčochář, Miroslav ; Zámostný, P. ; Grof, Z. ; Štěpánek, F. ; Schöngut, M. ; Havlica, Jaromír
Pigments are mostly nanometric powder of anisometric particles providing complex rheological behaviour. The interparticle forces of grains (> 100 μm) are based on direct contact, which is mainly influenced by the particle size and shape. On the other hand powder (< 4 μm) and especialy nanometric powder (< 100 nm) is influenced mainly by electrostatic charges and by moisture (respectively by the liquid and solid bridges forming). However the morphology affects the surface area and thus the distribution of surface charge and\nthe moisture content on/in single particle. Last but not least, it is also good to know the history of the powder, i.e. the effect of aging and the memory of the powder on the strength of the material. The nanometric powder TiO2 was chosen as a demonstration material and measuring device was FT4 powder rheometer.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22018011012520 - PDF
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